it is real easy, check some of my diaries, i have twisted them ,pinched them, cut them ect. real easy you give the stem a light pinch and soft bend, you will feel the stem between your fingers until a small crunch, research videos ect. the reasons why i do the pinch is i want to strengthen that main cola area so it grows big and fat, i also pinch it so that stem can hold the top cola good. but you would be surprised what cannabis plants can take. your plant is looking real healthy and happy by the way